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Post‐collisional magmatism contains important clues for understanding the reworking and growth of continental crust, as well as lithospheric delamination and orogenic collapse. Early Devonian magmatism has been identified in the North Qilian Orogenic Belt (NQOB). This paper reports an integrated study of petrology, whole‐rock geochemistry, Sm‐Nd isotope and zircon U‐Pb dating, as well as Lu‐Hf isotopic data, for two Early Devonian intrusive plutons. The Yongchang and Chijin granites yield zircon U‐Pb ages of 394–407 Ma and 414 Ma, respectively. Both of them are characterized by weakly peraluminous to metaluminous without typical aluminium‐rich minerals, LREE‐enriched patterns with negative Eu anomalies and a negative correlation between P2O5 and SiO2 contents, consistent with geochemical features of I‐type granitoids. Zircons from the studied granites display negative to weak positive εHf(t) values (–5.7 to 2.1), which agree well with those of negative εNd(t) values (−6.4 to −2.9) for the whole‐rock samples, indicating that they were derived from the partial melting of Mesoproterozoic crust. Furthermore, low Sr/Y ratios (1.13–21.28) and high zircon saturation temperatures (745°C to 839°C, with the majority being >800°C) demonstrated a relatively shallow depth level below the garnet stability field and an additional heat source. Taken together, the Early Devonian granitic magmatism could have been produced by the partial melting of ancient crustal materials heated by mantle‐derived magmas at high‐temperature and low‐pressure conditions during post‐collisional extensional collapse. The data obtained in this study, when viewed in conjunction with previous studies, provides more information about the tectonic processes that followed the closure of the North Qilian Ocean. The tectonic transition from continental collision to post‐collisional delamination could be constrained to ∼430 Ma, which is provided by the sudden decrease of Sr/Y and La/Yb ratios and an increase in zircon εHf(t) values for granitoids. A two‐stage tectonic evolution model from continental collision to post‐collisional extensional collapse for the NQOB includes (a) continental collision and crustal thickening during ca. 455–430 Ma, characterized by granulite‐facies metamorphism and widespread low‐Mg adakitic magmatism; (b) post‐collisional delamination of thickened continental crust and extensional collapse of orogen during ca. 430–390 Ma, provided by coeval high‐Mg adakitic magmatism, A‐type granites and I‐type granitoids with low Sr‐Y ratios. [ABSTRACT FROM AUTHOR]

The Nanyuan Formation contains information related to the Mesozoic tectonic transformation. In this study, three representative profiles were surveyed from the Nanyuan Formation, and multiple analyses were conducted. Zircon U‐Pb dating yielded their ages as approximately 158–146 Ma. The volcanic rocks are enriched in Rb, Th, U, K, and Pb and depleted in Nb, Ta, P, and Ti, implying their affinity for I‐type granites. The εNd(t) values (–8.3 to −6.0), (87Sr/86Sr)i values (0.7077–0.7094) of the volcanic rock, and εHf(t) values (–8.71 to 0.12) of the Mesozoic zircons suggest that the Nanyuan Formation magma originated in the lower crust with the involvement of depleted mantle materials. The parent rocks of the rhyolitic and dacitic volcanic rocks formed by partial melting of basement rocks in South China and the andesitic volcanic rocks were derived from partial melting of the metasomatites generated by slab‐mantle interaction. The fractional crystallization also played an important role in later stage. Discrimination diagrams of the volcanic rocks indicated that they formed in a volcanic arc environment. Combined with previous data, the Nanyuan Formation recorded subduction of the Paleo‐Pacific Plate before regional tectonic transformation. The compressive stress field endured until the end of the Late Jurassic. [ABSTRACT FROM AUTHOR]

We investigated the meta‐gabbronorites in Liangcheng and used detailed petrography, geochemistry, zircon geochronological and in‐situ Hf isotopic studies to clarify their formation and metamorphic ages, petrogenesis, tectonic setting and provide constraints on the tectonic evolution of Khondalite Belt (KB). The zircon U‐Pb dating results show that the meta‐gabbronorites crystallized at ~1.94 Ga and were metamorphosed at ~1.91–1.89 Ga. They can be subdivided into the low‐Mg and high‐Mg groups. The low‐Mg meta‐gabbronorites contain relatively lower MgO and higher SiO2 contents than high‐Mg meta‐gabbronorites. They are enriched in light rare earth elements and large ion lithophile elements, depleted in high field strength elements, and exhibit positive (high‐Mg meta‐gabbronorites) and negative (low‐Mg meta‐gabbronorites) Sr and Eu anomalies. The zircon in‐situ εHf(t) of meta‐gabbronorites is 0.07–4.12, with Hf model ages (TDM) of 2169–2400 Ma. The meta‐gabbronorites in Liangcheng originated from the asthenospheric mantle and experienced fractional crystallization of olivine, orthopyroxene, clinopyroxene, and plagioclase. They were contaminated by the crustal rocks (mainly khondalite series) during ascent, especially for low‐Mg gabbronorites. The ridge subduction is the most plausible tectonic setting for meta‐gabbronorites, indicating the eastern segment of KB was in a ridge subduction setting at ~1.94 Ga following an orogenic thickening event during a prolonged orogenic process. [ABSTRACT FROM AUTHOR]

A comprehensive study of zircon U‐Pb geochronology, in situ Hf isotopes, whole‐rock major and trace element geochemistry, and Nd isotopes was carried out for two Early Jurassic two‐mica granites (Longtang and Menglong) in the southern part of the Tengchong terrane, which is in the northern part of the larger Sibumasu terrane. We assess the origin of the granites and explore their possible genetic relationship to the Paleo‐Tethyan regime. LA‐ICP‐MS zircon U‐Pb dating shows that they were simultaneously emplaced in the Early Jurassic (ca. 199 Ma). They have SiO2 contents of 69.7–75.1 wt% and are mainly strongly peraluminous with alumina saturation index (ASI) values ranging from 1.06 to 1.46. They show similar Mg# (0.29–0.42) to experimental partial melts of metasedimentary rocks under continental pressure‐temperature (P‐T) conditions. They are enriched in light rare earth elements (LREEs) relative to heavy rare earth elements (HREEs), with moderately negative Eu anomalies and flat HREEs patterns. They show negative εNd(t) values (–9.0 to –12.4) and εHf(t) values (–8.0 to –9.1). Elemental and isotopic data suggest that they most likely to formed by muscovite‐dehydration melting of a metapelitic source at lower temperatures in the range of 700°C to 750°C. The granites might represent a post‐collisional tectonic setting response to Paleo‐Tethyan regime. [ABSTRACT FROM AUTHOR]

The Aqishan lead‐zinc deposit, located in the Jueluotag metallogenic belt of eastern Tianshan, Xinjiang, Northwest China, has a stratiform occurrence in the marine volcanic tuff of the Yamansu Formation. The ore body has a typical double‐layer structure, having a stratified, stratoid, lenticular upper part and a veined, stockwork‐like lower part. The occurrence of the upper orebody is consistent with that of the volcanic tuff wall rock. The ore minerals are mainly chalcopyrite, pyrite, sphalerite, galena and magnetite, the altered minerals mainly being silicified, such as sericite, chlorite, epidote, garnet. The garnetized skarn, being stratiform and stratoid, is closely related to the upper part of the orebody. Geological observations show that the limestone in the ore‐bearing Yamansu Formation is not marbleized and skarnized. Spatially, it is associated with the ferromanganese deposits in the marine volcanic rocks of the Yamansu Formation. These geological features reflect the likelihood that the Aqishan lead‐zinc deposit is a hydrothermal exhalation sedimentary deposit. The results from the EPMA show that the garnet is mainly composed of grossular–andradite series, contents being in a range of 34.791–37.8% SiO2, 32.493–34.274% CaO, 8.454–27.275% FeO, 0.012–15.293% Al2O3, 0.351–1.413% MnO, and lower values of 0.013–1.057% TiO2. The content of SiO2 vs. CaO and FeO vs. Al2O3 has a significant positive correlation. The results of ICP‐MS analysis for the garnet show that the REE pattern is oblique to right in general. The total amount of rare earth elements is relatively low, ΣREE = 71.045–826.52 ppm, which is relatively enriched for LREE and depleted for HREE. LREE/HREE = 8.66–4157.75, LaN/YbN = 23.51–984.34, with obvious positive Eu and Ce anomalies (δEu = 2.27–76.15, δCe = 0.94–1.85). This result is similar to the REE characteristics of ore‐bearing rhyolite volcanic rocks, showing that the garnet was formed in an oxidizing environment and affected by clear hydrothermal activity. The U‐Pb isotopic dating of garnet by fs‐LA‐HR‐ICP‐MS gives an age of 316.3 ± 4.4 Ma (MSWD = 1.4), which is consistent with the formation time of the Yamansu Formation. According to the study of deposit characteristics and geochemical characteristics, this study concludes that the Aqishan lead‐zinc deposit is a hydrothermal exhalation sedimentary deposit, the garnet being caused by hydrothermal exhalative sedimentation. [ABSTRACT FROM AUTHOR]

During the Late Cretaceous in the Eastern Mediterranean, the northern branch of the southern Neotethys was closed by multiple northward subductions. Of these, the most northerly located subduction created the Baskil continental arc at around 82–84 Ma. The more southerly and intra‐oceanic subduction, on the other hand, produced an arc‐basin system, the Yüksekova Complex, as early as the late Cenomanian–early Turonian. The abundant and relatively well‐studied basaltic rocks of this complex were intruded by dykes, sills and small stocks of felsic–intermediate rocks, not previously studied in detail. The intrusives collected from five different localities in the Elazığ region of eastern Turkey are all subalkaline, with low Nb/Y values. Most of them have been chemically classified as rhyodacites/dacites, whereas a small number appear to be andesites. In normal mid‐ocean‐ridge basalt (N‐MORB)‐normalised plots, the intrusives are characterised by relative enrichments in Th and La over Nb, Zr, Hf, Ti and high field strength elements (HREEs), indicating their derivation from a subduction‐modified source. While their relatively high, positive εNd(i) values (+6.4 and +7.2) might suggest a depleted mantle source for their ultimate origin, somewhat radiogenic Pb values indicate a sedimentary contribution to the source of the rocks. The overall geochemical characteristics indicate their generation in an oceanic arc setting. The zircon U‐Pb Laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) data obtained from five felsic‐intermediate rock samples yielded intrusion dates of 80–88 Ma. This suggests that the Elazığ oceanic arc‐related intrusives are slightly younger than those of the Yüksekova arc‐basin system, but coeval with the Baskil continental arc. However, the felsic–intermediate intrusives show different geochemical characteristics (oceanic arc‐type, with a lack of crustal contamination) to those of the Baskil continental arc. This indicates that these two igneous systems are unrelated and likely developed in different tectonic settings. This, in turn, supports a geodynamic model in which the northern strand of the southern Neotethys was consumed by multiple northward subductions. [ABSTRACT FROM AUTHOR]

Late Paleozoic volcanic rocks are well exposed in the Yining Block, NW China, and are predominately composed of andesites, rhyolites and volcaniclastics as well as minor basalts. Study of the petrology, whole‐rock geochemistry and zircon U‐Pb dating for the Early Carboniferous alkaline basalts from Wusun Mountain, western Yining Block, constrains their petrogenesis and tectonic evolution. The alkaline basalts consist mainly of plagioclases, mostly albite and labradorite, as well as clinopyroxenes and olivines; zircon U‐Pb dating indicates their formation at ca. 350 Ma. Geochemically, the basaltic samples have low SiO2 contents, and high TiO2, Al2O3 and alkaline contents, coupled with high Na2O/K2O ratios, displaying an alkaline basalt affinity. They show remarkable LILE enrichment and HFSE depletion. Meantime, these samples have relatively high TFe2O3, MgO, and Mg# values as well as Ni and Cr, relatively high Sm/Yb and U/Th, suggesting origination from a mantle source metasomatized by slab fluids. They formed in a transitional tectonic setting from arc to intraplate, showing a typical affinity of back‐arc basin basalts. The alkaline basalts were likely generated in a nascent back‐arc extension setting resulting from slab rollback of the southern Tianshan oceanic lithosphere. A bi‐directional subduction model seems more reasonable for the evolution of the southern Tianshan Ocean. These new data will provide a new tectonic model for Late Paleozoic tectonic evolution of the western Yining Block. [ABSTRACT FROM AUTHOR]

The Yaojialing deposit is the first large‐scale Zn–Au–Cu polymetallic skarn deposit located in the Shatanjiao ore field of the Tongling area in the Middle–Lower Yangtze belt. It has distinct metallogenic characteristics and is clearly different from the known skarn Cu–Au deposits in the Tongling area and the Middle–Lower Yangtze belt. Previous studies of the Yaojialing deposit have included rock geochemistry, alteration and mineralization characteristics, as well as metallogenesis and metallogenic models. However, there are still numerous problems concerning the coexistence of multiple elements, metallogenetic specialization of the magma and the metallogenic model. In this study, using the latest production exploration work on the deposit, we investigated the Yaojialing deposit including its geological characteristics, petrography, LA–ICP MS zircon U–Pb dating and whole rock geochemistry. Two kinds of magmatic rocks have been distinguished for the first time in the deposit, amongst which the granodiorite porphyry exposed on the surface of the mining area, which is the host rock of the veined lead–zinc ore body, is the wall‐rock intrusion; and the deep concealed quartz monzonite porphyry is the causative intrusion, the distribution of orebodies and wall‐rock alteration characteristics showing regular zoning around the quartz monzonite porphyry. The 206Pb/238U weighted average age of the granodiorite porphyry is 140.2 ± 1.0 Ma (MSWD = 0.85, n = 13) by LA–ICP MS zircon U–Pb dating, while the quartz monzonite porphyry is 138.9 ± 1.2 Ma (MSWD = 0.60, n = 16), which is consistent with petrographic evidence. The geochemical characteristics show that the quartz monzonite porphyry is a high‐K calc‐alkaline series peraluminous rock. The trace element characteristics show that the quartz monzonite porphyry is enriched in LILE such as K, Rb, Sr, Ba and LREE, yet depleted in HFSE such as Nb, Ta, P and Ti. The Yaojialing deposit shows the mineralization characteristics of proximal skarn and distal skarn, having the common characteristics of 'multi‐storey' and 'Trinity' metallogenic models. [ABSTRACT FROM AUTHOR]

The Feidong district is located in the southern segment of the Tan–Lu fault zone that separates the South China Block (NCB) from the North China Craton (NCC). We report zircon U‐Pb geochronology and Hf isotope data, as well as whole‐rock geochemistry for Xishanyi granodiorite and Jianshan granite in the Feidong district. Zircon U‐Pb dating results show that the emplacement ages of the Xishanyi and Jianshan intrusions are 124 ± 3 Ma and 130 ± 1 Ma respectively, coeval with magmatic events linked to large‐scale lithospheric thinning in eastern China. The whole‐rock geochemistry of the Xishanyi and Jianshan intrusions demonstrate that they are peraluminous, high potassium calc‐alkaline I‐type granites with adakitic characteristics. Both intrusions underwent weak crustal assimilation during emplacement. The in situ zircon ∊Hf(t) values of the Xishanyi granodiorites range from –26.4 to –21.8, with TDM2 model ages of 2552 to 2841 Ma. The in situ zircon ∊Hf(t) values of the Jianshan granite are from –27.5 to –23.0 with TDM2 model ages of 2632 to 2904 Ma. The peak age of inherited zircon grains from the Xishanyi granodiorite and the Jianshan granite were ∼2.07 Ga and ∼1.94 Ga, respectively. After compared with the regional magmatism, we suggest that both the Xishanyi and Jianshan granitoid intrusions were derived from partial melting of the NCC lower crust. [ABSTRACT FROM AUTHOR]

Post‐collisional volcanic rocks of Mesozoic age occur in the regions adjacent to Gerze, part of the southern Qiangtang Terrane of northern Tibet, China. Geochronological, geochemical, and whole‐rock Sr‐Nd isotopic analyses were performed on the volcanic rocks to better characterize their emplacement age and models for their origin. Laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) U‐Pb zircon analyses yielded consistent ages ranging from 123.1±0.94 Ma to 124.5±0.89 Ma for six volcanic rocks from the study area. The intermediate volcanic rocks belong to the alkaline and sub‐alkaline magma series in terms of K2O+Na2O contents (5.9%–9.0%), and to the shoshonitic and calc‐alkaline series on the basis of their high K2O contents (1.4%–3.3%). The Gerze volcanic rocks are characterized by the enrichment of light rare earth elements [(La/Yb)N=34.9–49.5] and large–ion lithophile elements (e.g., Rb, Ba, Th, U, K, Pb, and Sr), slightly negative Eu anomalies (Eu/Eu*=0.19–0.24), and negative anomalies in high field strength elements (e.g., Nb, Ta, Hf and Ti), relative to primitive mantle. The samples show slightly elevated (87Sr/86Sr)i values that range from 0.7049 to 0.7057, and low ∊Nd(t) values from –0.89 to –2.89. These results suggest that the volcanic rocks studied derived from a compositionally heterogeneous mantle source and that their parent magmas were basaltic. The more mafic, parental magmas to the Gerze volcanic rocks likely underwent fractional crystallization of clinopyroxene, hornblende, biotite, and potassium feldspar, during ascent, with little to no crustal contamination, prior to their eruption/emplacement. While these volcanic rocks exhibit geochemical signatures typical of magmas formed in a destructive plate‐margin setting, it is plausible that their mantle source might also have acquired such characteristics in an earlier episode of subduction. [ABSTRACT FROM AUTHOR]

The metasedimentary Lujiapuzi Formation crops out along the northeastern margin of the North China Craton, close to the Yan‐Liao Rift. The age and tectonic setting of the formation, and its relationship with the Yan‐Liao Rift are currently unclear. Here we present detrital zircon U‐Pb ages, and Hf isotopic and geochemical data for the Lujiapuzi Formation to constrain the timing of deposition, the provenance of the formation, and the regional stratigraphy relationship. Zircon U‐Pb dating constrains the timing of deposition of the Lujiapuzi Formation to younger than 1780 Ma, and indicates that most grains were sourced from the Longgang Block and the Paleoproterozoic Liao‐Ji Belt. Detailed field investigations and a correlation of the regional stratigraphy reveal that much of the Lujiapuzi Formation is equivalent to the Tuanshanzi Formation in the Yan‐Liao Rift; the lower section may represent the earliest sediments deposited within the Fanhe Basin. Based on these results and the findings of previous studies, we suggest that the base of the Changcheng System has an age of 1.80 Ga. Zircon Hf isotopic data indicate that the main period of crustal growth along the northeastern margin of the North China Craton occurred at 3.2–2.5 Ga, with a peak at 2.9–2.7 Ga. [ABSTRACT FROM AUTHOR]

The Tianshan Orogen (TO) is one of the largest typical accretionary orogenic belts in the world. Of which, the late Paleozoic was a critical era to understand the tectonic and geodynamic transition from accretion to collision. However, the late Paleozoic tectonic evolutionary history, especially for the time of the ocean‐continent transition, is still debated although the origin and tectonic settings for the Paleozoic volcanic, felsic igneous magmatism in TO and reginal geology have been done in the last decades. In contrast, the researches on the mafic dykes in TO was not systematically carried out till now. Reginal‐scale mafic dykes are commonly regarded as the products created in a extensional setting, and used to identify the major tectonic events such as rifting and continental break‐up and further trace the mantle natures and geodynamic mechanism (Halls, 1982; Bleeker and Ernst, 2006; Li et al., 2008; Ernst et al., 2010; Srivastava, 2011; Hou, 2012; Peng, 2015; Peng et al., 2019). There are widespread late Paleozoic mafic dykes beside the huge of intermediate‐acid igneous rocks in the TO, being an idea object to reveal the extensional events, tectonic evolution and the mantle nature and geodynamic processes. We present the ICP‐MS in situ zircon U–Pb dating, Lu‐Hf and whole‐rock Sr‐Nd isotopes as well as the geochemistry data for these mafic dykes to better constraint their petrogenesis and mantle nature. New zircon U‐Pb dating for 12 samples from the representative basic dykes and basalts yield three distinct stages of ∼332 Ma, 316–302 Ma and 288–282 Ma, respectively. In which, the first stage of mafic dykes is mainly occurred in both East Tianshan Orogen (ETO) and West Tianshan Orogen (WTO), and composed of dolerite with minor basalts. The second stage of mafic dyke also can be found in both ETO and WTO. However, in contrast to the first stage of mafic dykes, they have relatively variable rock types from the dolerite/or gabbros to gabbroic diorite. The third stage of mafic dykes are slightly intermediate in composition, and chiefly consist of andesitic‐basaltic dolerite with some diorites. They are widely developed not only in both ETO and WTO, but also in the Beishan area to the east of the ETO, indicating a large‐scale mafic magmatism in Tianshan and adjacent areas. Geochemically, first stage of mafic dykes is characterized by low SiO2 content of 47.23–47.09 wt% in ETO and 48.69–51.31 wt% in WTO with the variable Mg# values varying from 48.24 to 60.8 in ETO and from 54.26 to 59.14 in WTO. They evolved towards Fe‐depletion along the calc‐alkaline trend. Some of dykes display a slightly negative Sr anomalies and minor negative Eu anomalies (δEu=0.84–0.96), indicating a calc‐alkaline series with a the clinopyroxene‐ and plagioclase‐dominated fractionation. While, those sharing the positive Eu and Sr anomalies are most likely indicative of some degree of plagioclase accumulation. All mafic dykes have relative higher and variable LREE {(La/Yb)N=1.61–9.39} as well as LILEs (Rb, Ba and K) and depletion in HFSE with evident peak of Pb and valley of Nb. They show coherent zircon Hf and whole rock Sr‐Nd‐Pb isotopic composition, with a low (206Pb/204Pb)i (18.79) and variable (87Sr/86Sr)i (0.7033–0.7060) and positive variable ∊Nd(t) from 3.69 to 10.14 and ∊Hf(t) from 3.24 to 13.09. In addition, these mafic dykes have high Zr/Nb (13.6–48.6, average 30.9), and low La/Nb (2.1–5.1, average 3.2) ratios, showing a similarity to those of MORB mantle melts (Zr/Nb=30, La/Nb=1.07) (Sun and McDonough, 1989) rather than OIB asthenospheric mantle melts (Zr/Nb=5.3, La/Nd=0.77, Sun and McDonough, 1989). Their higher Zr/Y (2.5–6.8, average 4.0) and Nb/Y (0.1–0.5, average 0.2) ratios further suggest that they were derived from partial melting of a depleted lithospheric mantle (Bradshaw and Eugene, 1993; Condie, 2005). However, their Nb/La (0.20–0.49, average 0.35), Nb/U (3.3–17.8, average 8.6) and Ce/Pb (1.1–11.8, average 6.84) ratios are very low, much close to those of the continental crust (Nb/La=0.4, Nb/U=6.15, Ce/Pb=3.9, Rudnick and Gao, 2003), indicating crustal contamination (Xia and Li, 2014). All geochemistry and isotope composition favor that they were derived from a heterogeneous mantle source mixed by both depleted lithosphere mantle and EMI, and then experienced crustal contamination during the magma ascending. Second stage of mafic dykes have variable SiO2 content of 46.71–54.92 wt% in ETO and 48.53–52.59 wt% in WTO and variable Mg# values from 45.94 to 55.74 in ETO and from 27.04 to 53.64 in WTO and FeOT/MgO values higher than 1 (1.75–2.33 in ETO, 1.71–5.35 in WTO), showing a calc‐alkaline series in ETO and tholeiitic series in WTO associated with a certain extent magmatic evolution. However, many of the chemical and Sr‐Nd‐Hf isotopic features are in accord with those of first stage of mafic dykes. They are characterized by the right deviation REE pattern with slightly high LREE, moderate fraction between LREE and HREE {(La/Yb)N =2.55–7.52} and Eu (δEu =0.85–1.10) anomalies as well as the enrichment in LILEs (Rb, Ba and K) and poor HFSEs with obvious depletion of Nb and peak of Pb. Furthermore, they, just like first stage mafic dyke, have relatively depleted zircon Hf and whole rock Nd isotopic composition with a higher ∊Nd(t) (2.68–9.73) and ∊Hf(t) (2.55–15.46) but variable (87Sr/86Sr)i of 0.7036–0.7157 and high (206Pb/204Pb)i of 19.26‐19.78. They also display a higher Zr/Nb (10.3‐50.7, average 22.3), La/Nb (1.1‐3.7, average 2.51), Zr/Y (2.4–10.3, average 5.3) and Nb/Y (0.05–0.5, average 0.3) as well as low Nb/La (0.27–0.91, average 0.46), slightly high Nb/U (4.59–26.80, average 13.28) and Ce/Pb (2.21–16.94, average 7.71) ratios. All geochemistry and isotopic composition suggest they have a mantle source similar to those of first stage of mafic dykes, and originated from partial melting of a heterogeneous mixing source composed of the depleted lithosphere mantle and EMII. The third stage of mafic dykes, like the second stage of mafic dyke, have variable SiO2 ranging from 46.39 to 52.69 wt% in ETO and 49.62 to 54.68 wt% in Beishan area, and belong to a calc‐alkaline series. They have moderate Mg# values from 41.86 to 55.24 in ETO and from 41.7 to 55.28 in Beishan area, and exhibit negative Sr anomalies and medium negative or slight positive Eu anomalies (Eu/Eu=0.56–1.08), indicating plagioclase‐dominated fractionation during magma evolution. They are enriched in LILEs and LREE {(La/Yb)N = 3.16–6.38} and depleted in HFSEs with the valleys of Nb and Ti and a peak of Pb. They have narrow (87Sr/86Sr)i (0.7040 to 0.7050) and low (206Pb/204Pb)i (18.41). Their eNd(t) values are positive and variable, ranging from 5.36 to 10.36. While, their eHf(t) range from −7.13 to 18.33. Furthermore, like early mafic dykes, they are also characterized by the higher Zr/Nb (13.0‐29.8, average 20.57), La/Nb (1.0‐3.4, average 2.35), Zr/Y (3.2–6.8, average 4.8) and Nb/Y (0.1–0.4, average 0.3) as well as low Nb/La (0.29–1.00, average 0.50), Nb/U (3.21–17.53, average 7.92) and Ce/Pb (1.73–10.79, average 6.75) ratios. All suggest they were derived from a source inherited from early heterogeneous depleted lithosphere mantle involved in EMI and subjected crustal contamination during magma ascending. In summary, the late Paleozoic mafic dykes widely developed in the TO can be subdivided three distinct stages of mafic magmatism, and shear the consistent rock associations, petrogeochemistry and isotopic compositions. Three stages of mafic dykes are relatively enriched in LREE, LILEs and depleted in HFSEs with the valleys of Nb and Ti and a peak of Pb and slightly fractionation between LREE and HREE. They are coherently characterized by positive and variable ∊Nd(t) and ∊Hf(t) values, low (206Pb/204Pb)i and variable (87Sr/86Sr)i isotope ratios. Furthermore, they have higher Zr/Nb, La/Nb, Zr/Y and Nb/Y and low Nb/La, Nb/U and Ce/Pb ratios. All suggest that these late Paleozoic mafic dykes were mainly originated from a long‐lived unitary heterogeneous lithospheric mantle mixed by EMI and possible minor MEII and experienced varying degrees crustal contamination during the magma ascending. Consequently, based our new geochemical and Sr‐Nd‐Pb‐Hf isotopic data and combined with the previous studies on the reginal geology and widespread late Paleozoic post‐collisional magmatism (Xu et al., 2013; Xia et al., 2004, 2013), it can be proposed that the arc‐microcontinents collision in the TO started at least before the early late Carboniferous (Serpukhovian), and the mafic dykes with three distinct stages of ∼332 Ma, 316–302 Ma and 288–282 Ma were generated in a lithosphere extensional settings after arc‐microcontinents collision from late Carboniferous to early Permian. [ABSTRACT FROM AUTHOR]

The Tianshan Orogen (TO) is one of the largest typical accretionary orogenic belts in the world. Of which, the late Paleozoic was a critical era to understand the tectonic and geodynamic transition from accretion to collision. However, the late Paleozoic tectonic evolutionary history, especially for the time of the ocean‐continent transition, is still debated although the origin and tectonic settings for the Paleozoic volcanic, felsic igneous magmatism in TO and reginal geology have been done in the last decades. In contrast, the researches on the mafic dykes in TO was not systematically carried out till now. Reginal‐scale mafic dykes are commonly regarded as the products created in a extensional setting, and used to identify the major tectonic events such as rifting and continental break‐up and further trace the mantle natures and geodynamic mechanism (Halls, 1982; Bleeker and Ernst, 2006; Li et al., 2008; Ernst et al., 2010; Srivastava, 2011; Hou, 2012; Peng, 2015; Peng et al., 2019). There are widespread late Paleozoic mafic dykes beside the huge of intermediate‐acid igneous rocks in the TO, being an idea object to reveal the extensional events, tectonic evolution and the mantle nature and geodynamic processes. We present the ICP‐MS in situ zircon U–Pb dating, Lu‐Hf and whole‐rock Sr‐Nd isotopes as well as the geochemistry data for these mafic dykes to better constraint their petrogenesis and mantle nature. New zircon U‐Pb dating for 12 samples from the representative basic dykes and basalts yield three distinct stages of ∼332 Ma, 316–302 Ma and 288–282 Ma, respectively. In which, the first stage of mafic dykes is mainly occurred in both East Tianshan Orogen (ETO) and West Tianshan Orogen (WTO), and composed of dolerite with minor basalts. The second stage of mafic dyke also can be found in both ETO and WTO. However, in contrast to the first stage of mafic dykes, they have relatively variable rock types from the dolerite/or gabbros to gabbroic diorite. The third stage of mafic dykes are slightly intermediate in composition, and chiefly consist of andesitic‐basaltic dolerite with some diorites. They are widely developed not only in both ETO and WTO, but also in the Beishan area to the east of the ETO, indicating a large‐scale mafic magmatism in Tianshan and adjacent areas. Geochemically, first stage of mafic dykes is characterized by low SiO2 content of 47.23–47.09 wt% in ETO and 48.69–51.31 wt% in WTO with the variable Mg# values varying from 48.24 to 60.8 in ETO and from 54.26 to 59.14 in WTO. They evolved towards Fe‐depletion along the calc‐alkaline trend. Some of dykes display a slightly negative Sr anomalies and minor negative Eu anomalies (δEu=0.84–0.96), indicating a calc‐alkaline series with a the clinopyroxene‐ and plagioclase‐dominated fractionation. While, those sharing the positive Eu and Sr anomalies are most likely indicative of some degree of plagioclase accumulation. All mafic dykes have relative higher and variable LREE {(La/Yb)N=1.61–9.39} as well as LILEs (Rb, Ba and K) and depletion in HFSE with evident peak of Pb and valley of Nb. They show coherent zircon Hf and whole rock Sr‐Nd‐Pb isotopic composition, with a low (206Pb/204Pb)i (18.79) and variable (87Sr/86Sr)i (0.7033–0.7060) and positive variable ∊Nd(t) from 3.69 to 10.14 and ∊Hf(t) from 3.24 to 13.09. In addition, these mafic dykes have high Zr/Nb (13.6–48.6, average 30.9), and low La/Nb (2.1–5.1, average 3.2) ratios, showing a similarity to those of MORB mantle melts (Zr/Nb=30, La/Nb=1.07) (Sun and McDonough, 1989) rather than OIB asthenospheric mantle melts (Zr/Nb=5.3, La/Nd=0.77, Sun and McDonough, 1989). Their higher Zr/Y (2.5–6.8, average 4.0) and Nb/Y (0.1–0.5, average 0.2) ratios further suggest that they were derived from partial melting of a depleted lithospheric mantle (Bradshaw and Eugene, 1993; Condie, 2005). However, their Nb/La (0.20–0.49, average 0.35), Nb/U (3.3–17.8, average 8.6) and Ce/Pb (1.1–11.8, average 6.84) ratios are very low, much close to those of the continental crust (Nb/La=0.4, Nb/U=6.15, Ce/Pb=3.9, Rudnick and Gao, 2003), indicating crustal contamination (Xia and Li, 2014). All geochemistry and isotope composition favor that they were derived from a heterogeneous mantle source mixed by both depleted lithosphere mantle and EMI, and then experienced crustal contamination during the magma ascending. Second stage of mafic dykes have variable SiO2 content of 46.71–54.92 wt% in ETO and 48.53–52.59 wt% in WTO and variable Mg# values from 45.94 to 55.74 in ETO and from 27.04 to 53.64 in WTO and FeOT/MgO values higher than 1 (1.75–2.33 in ETO, 1.71–5.35 in WTO), showing a calc‐alkaline series in ETO and tholeiitic series in WTO associated with a certain extent magmatic evolution. However, many of the chemical and Sr‐Nd‐Hf isotopic features are in accord with those of first stage of mafic dykes. They are characterized by the right deviation REE pattern with slightly high LREE, moderate fraction between LREE and HREE {(La/Yb)N =2.55–7.52} and Eu (δEu =0.85–1.10) anomalies as well as the enrichment in LILEs (Rb, Ba and K) and poor HFSEs with obvious depletion of Nb and peak of Pb. Furthermore, they, just like first stage mafic dyke, have relatively depleted zircon Hf and whole rock Nd isotopic composition with a higher ∊Nd(t) (2.68–9.73) and ∊Hf(t) (2.55–15.46) but variable (87Sr/86Sr)i of 0.7036–0.7157 and high (206Pb/204Pb)i of 19.26‐19.78. They also display a higher Zr/Nb (10.3‐50.7, average 22.3), La/Nb (1.1‐3.7, average 2.51), Zr/Y (2.4–10.3, average 5.3) and Nb/Y (0.05–0.5, average 0.3) as well as low Nb/La (0.27–0.91, average 0.46), slightly high Nb/U (4.59–26.80, average 13.28) and Ce/Pb (2.21–16.94, average 7.71) ratios. All geochemistry and isotopic composition suggest they have a mantle source similar to those of first stage of mafic dykes, and originated from partial melting of a heterogeneous mixing source composed of the depleted lithosphere mantle and EMII. The third stage of mafic dykes, like the second stage of mafic dyke, have variable SiO2 ranging from 46.39 to 52.69 wt% in ETO and 49.62 to 54.68 wt% in Beishan area, and belong to a calc‐alkaline series. They have moderate Mg# values from 41.86 to 55.24 in ETO and from 41.7 to 55.28 in Beishan area, and exhibit negative Sr anomalies and medium negative or slight positive Eu anomalies (Eu/Eu=0.56–1.08), indicating plagioclase‐dominated fractionation during magma evolution. They are enriched in LILEs and LREE {(La/Yb)N = 3.16–6.38} and depleted in HFSEs with the valleys of Nb and Ti and a peak of Pb. They have narrow (87Sr/86Sr)i (0.7040 to 0.7050) and low (206Pb/204Pb)i (18.41). Their eNd(t) values are positive and variable, ranging from 5.36 to 10.36. While, their eHf(t) range from −7.13 to 18.33. Furthermore, like early mafic dykes, they are also characterized by the higher Zr/Nb (13.0‐29.8, average 20.57), La/Nb (1.0‐3.4, average 2.35), Zr/Y (3.2–6.8, average 4.8) and Nb/Y (0.1–0.4, average 0.3) as well as low Nb/La (0.29–1.00, average 0.50), Nb/U (3.21–17.53, average 7.92) and Ce/Pb (1.73–10.79, average 6.75) ratios. All suggest they were derived from a source inherited from early heterogeneous depleted lithosphere mantle involved in EMI and subjected crustal contamination during magma ascending. In summary, the late Paleozoic mafic dykes widely developed in the TO can be subdivided three distinct stages of mafic magmatism, and shear the consistent rock associations, petrogeochemistry and isotopic compositions. Three stages of mafic dykes are relatively enriched in LREE, LILEs and depleted in HFSEs with the valleys of Nb and Ti and a peak of Pb and slightly fractionation between LREE and HREE. They are coherently characterized by positive and variable ∊Nd(t) and ∊Hf(t) values, low (206Pb/204Pb)i and variable (87Sr/86Sr)i isotope ratios. Furthermore, they have higher Zr/Nb, La/Nb, Zr/Y and Nb/Y and low Nb/La, Nb/U and Ce/Pb ratios. All suggest that these late Paleozoic mafic dykes were mainly originated from a long‐lived unitary heterogeneous lithospheric mantle mixed by EMI and possible minor MEII and experienced varying degrees crustal contamination during the magma ascending. Consequently, based our new geochemical and Sr‐Nd‐Pb‐Hf isotopic data and combined with the previous studies on the reginal geology and widespread late Paleozoic post‐collisional magmatism (Xu et al., 2013; Xia et al., 2004, 2013), it can be proposed that the arc‐microcontinents collision in the TO started at least before the early late Carboniferous (Serpukhovian), and the mafic dykes with three distinct stages of ∼332 Ma, 316–302 Ma and 288–282 Ma were generated in a lithosphere extensional settings after arc‐microcontinents collision from late Carboniferous to early Permian. [ABSTRACT FROM AUTHOR]

Investigation of the petrogenesis and the origin of zircons from the volcanic rocks of the Liujiaping Group of the back-Longmenshan tectonic belt in the northwest margin of the Yangtze Block is conducted by analysis of U-Pb geochronology and geochemistry. Results show that selected zircons are characterized by internal oscillatory zonings and high Th/U ratios (0.43-1.18), indicating an igneous origin. Geochronological results of LA-ICP-MS U-Pb dating of the Liujiaping Group zircons yield an age of 809 ± 11 Ma (MSWD = 2.2), implying that the volcanic rocks were formed in the Late Neoproterozoic. Geochemical analysis shows that the rocks are calc-alkaline, supersaturated in Al, and metaluminous to weakly peraluminous. Rare-earth elements are present at high concentrations (96.04-265.48 ppm) and show a rightward incline and a moderately negative Eu anomaly, similar to that of continental rift rhyolite. Trace element geochemistry is characterized by evident negative anomalies of Nb, Ta, P, Th, Ti, inter alia, and strong negative anomalies of K, Rb, Sr, et al. We conclude that the Liujiaping Group volcanic rocks resulted from typical continental crust source petrogenesis and were formed in a continental margin setting, which had no relation to subduction, and thus, were the products of partial melting of the lower crust due to crustal thickening caused by active continental margin subduction and arc-continent collision orogeny in the northwestern Yangtze Block and were triggered by the breakup of the Rodinia supercontinent during the Neoproterozoic. [ABSTRACT FROM AUTHOR]

The article focuses on uranium-lead (U-Pb) dating-based geochronology and geochemistry of zircon from the Saima-Bailinchuan Alkaline Intrusion (SBAI) in eastern Liaoning, China. It states that main rock types in the SBAI are alkaline syenite and aegirine-nepheline syenite, and further mentions that the genesis of the SBAI is the mixed crust and mantle-type, the latter is the major one.

Located in the northern part of the Xinlin-Xiguitu suture zone, geochemistry and geochronology of the Xinlin ophiolite provide a unique opportunity to determine the the evolution of the eastern Xing'an-Mongolian Orogenic Belt. The Xinlin ophiolite was initially constrained roughly 21.5 km southeast of the Xinlin town by the First Regional Geological Survey Party of Heilongjiang Province. Subsequent work has shown that the mafic and ultramafic rocks in the adjacent Tayuan town was congenetic with the Xinlin ophiolite (Fig. 1). Over the past three years we have conducted a series of studies to the Xinlin ophiolite with the aim to better understand its characteristic and tectonic implications. The present work is is to provide our preliminary geochemical data of the mafic rocks of the Xinlin ophiolite and possible 'congenetic' mafic rocks in the Tayuan town. The mafic rocks of the Xinlin ophiolite including the gabbro, diabase and metabasalt show flat REE pattern [(La/Yb)N = 0.68∼1.58] and no Eu anomalies, which are transitional between normal and enriched mid-ocean ridge basalts (N-MORB and E-MORB). They also exhibit flat patterns from Ba to Yb in the trace elements spider diagram, which lie between those of typical E-MORB and N-MORB but closer to the former. The mafic rocks in the Tayuan town consist mainly of hornblende gabbro with alkaline affinity and are characterized by enriched in light rare earth elements and large ion lithophile elements, depleted in heavy rare earth elements and high field strength elements (Fig. 2). The obvious differences in the geochemical characteristics indicate that the mafic rocks in the Tayuan town may not be cogenetic with those of the Xinlin ophiolite. This was further corroborated by their different formation time. Our zircon U-Pb dating indicates that the gabbro in the Tayuan town was emplaced during the late Carboniferous (∼310 Ma; Fig. 3), significantly younger than the recently reported U-Pb ages for the mafic rocks of the Xinlin ophiolite (∼510 Ma; Feng, 2015). Therefore, the two units appear as independent bodies and their origin and tectonic implication need to be further examined. [ABSTRACT FROM AUTHOR]

The Zhou'an PGE-Cu-Ni deposit was recently discovered in the Qinling orogenic belt bound by the Yangtze and the North China Cratons. It is a blind deposit thoroughly covered by the Cenozoic alluvial sediments in the Nanyang Basin. As the first large PGE-Cu-Ni deposit discovered in the Qinling-Dabie-Sulu orogenic belt, its geological and geochemical characteristic, isotope age, genesis and tectonic setting are of wide concern in both scientific studies and ore exploration. In this contribution, we report the results obtained from a pioneering study. The Zhou'an ultramafic complex is ferruginous, with m/f = 4.79-5.08, and shows the nature of tholeiite series. It is rich in light rare earth elements, Rb, Th, U, La, Sm, Zr and Hf, and poor in heavy rare earth elements, Nd and Ta, suggesting an intraplate setting. It has high 87Sr/86Sr and low 143Nd/144Nd ratios. The ratios of Zr/Nb, La/Nb, Ba/Nb, Rb/Nb, Th/Nb, Th/La and Ba/La, suggest the magma originated from lithosphere mantle. The Fo values of olivine and Pd/Ir-Ni/Cu diagram suggest primary magma was High Mg basalt. The laser ablation inductively coupled plasma atomic emission spectroscopy zircon U-Pb age is 641.5 ± 3.7 Ma. [ABSTRACT FROM AUTHOR]

The metallogenetic porphyry bodies in the Nongping Au-Cu deposit, in the eastern Yanbian area, mainly include porphyritic granodiorite and biotite granodiorite porphyry. They are featured with high silicon and enrichment in sodium, and classified into sodic rocks of low-K tholeiitic basalt series. Except slightly low Sr content, the rock basically has the geochemical characteristics of the adakite: relatively high A12O3 content, relatively low MgO content, depletion in Y and Yb; relative enrichment in large ion lithophile elements (LILEs) and light rare-earth elements (LREEs), relatively low content of high field strength elements (HFSEs); positive Eu anomaly or weak negative Eu anomaly. In situ zircon dating technology LA-MC-ICP-MS was used to conduct single-grain zircon dating of biotite granodiorite porphyry, and the results show that the age of metallogenetic porphyry body is 100.04±0.88 Ma, indicating that the porphyry bodies were emplaced in the late Cretaceous period. According to the regional tectonic setting and the comparison with the same kind of deposits, we think that the metallogenetic porphyry bodies in the Nongping Au-Cu deposit have a close genetic connection with the subduction of the Pacific plate in the late Yanshanian period. The adakitic magma generated from partial melting of the subducting plate has high formation temperature, high oxygen fugacity, and volatile constituents' enrichment, so it is helpful for enrichment of metallogenetic elements and plays an important role in the formation of porphyry Au-Cu deposits in this region. [ABSTRACT FROM AUTHOR]

The granodiorites, monzogranites and diorites are widely developed in the Balikun area of Eastern Tianshan Orogen. Of which, LA–ICP–MS zircon U‐Pb isotopic dating from the diorites revealed that they were emplaced at 327∼333 Ma, representing an important period of magmatism in the Early Carboniferous. Geochemically, they are characterized by moderate SiO2 (51.33–62.48 wt%), high but variable MgO (2.04–11.16 wt%, average 5.35), higher Mg# (40–73) and TiO2 (0.67–1.29 wt%), Na2O/K2O (1.39–2.95) as well as variable Cr (2.49–675 ppm) and Ni (1.31–174 ppm), showing a geochemistry similar to those of high‐Mg diorites or sanukitoids. In addition, they are enriched in the LILE, poor HFSE with an evident negative Nb anomalies and a REE pattern of moderate fractionator between LREE and HREE without or weak negative Eu anomalies. Their ∊Hf(t) are positive (+3.63–+15.65), suggesting a source from the depleted mantle. In addition, they have high TiO2 and Pb, and large quantity of amphibolite and biotite, indicating that they were most likely derived from the partial melting of depleted mantle metasomatized by the slab‐derived melt under a hydrous condition. Consequently, combined with the contemporary volcanics and granitoids formed in the island arc settings, we proposed that the subduction was continued till Early Carboniferous in the Bogda‐Harlik tectonic belt. After that, wide occurrence of the post‐collisional A‐type granites and mafic‐ultramafic intrusions indicate this tectonic belt entered the post‐collisional environment from Late Carboniferous to Permian. [ABSTRACT FROM AUTHOR]

The North Qaidam orogenic belt (NQOB) lies at the northeast margin of Tibet Plateau, between the Qilian massif to the north and Qaidam massif to the south. It consists of predominantly gneisses and marbles with minor eclogite and garnet peridotite, and is known as an Early Paleozoic continental deep subduction ultrahigh pressure (UHP) metamorphic belt in northwest China. Recently some studies suggest that the NQOB experienced oceanic deep subduction prior to the continental deep subduction. However, the records of ocean events are rarely preserved because of the complex multi‐stage transformation. Therefore, whether the Early Paleozoic ocean exists and the formation, nature and evolution of the Early Paleozoic ocean in North Qaidam are still in controversies. In this contribution, we report a new discovered SSZ‐type ophiolite suite in Kaipinggou area, the western segment of the NQOB. The ophiolite is mainly composed of peridotite, gabbro, basalt, boninite, andesitic porphyrite and plagiogranite. In which, the basalt and homogeneous gabbro are both enriched in LILE and depleted in HFSE, and display flat or LREE‐depleted REE patterns, similar to the MORB‐like geochemical characteristics of fore‐arc basalts; the boninite exhibits characteristics of fore‐arc boninites with high Si and Mg, but low Ti and Ca contents; the andesitic porphyrite is enriched in LILE but depleted in HFSE, similar to island arc magmatic rocks. Rock assemblage and their geochemical characteristics suggest that this SSZ‐type ophiolite was formed in fore‐arc setting of intra‐oceanic arc. The plagiogranite is a low‐potassium tholeiite metaluminous granite with low trace elements contents, slight enrichment of LREE, depletion of HREE and positive Eu anomaly; combining with ∊Hf (t) values (13.8–17.1) of zircons, the plagiogranite could be originated from partial melting of gabbros. LA–ICP–MS zircon U–Pb dating yielded the crystallization ages of 535±2 Ma, 513±3 Ma and 510±3 Ma for two cumulate gabbros and one homogeneous gabbro, respectively, and a formation age of 492±8 Ma for the plagiogranite. All these data suggest the existence of an Early Paleozoic ocean in the North Qaidam, and the initial subduction of the oceanic slab occurred earlier than 535Ma. [ABSTRACT FROM AUTHOR]

The granodiorites, monzogranites and diorites are widely developed in the Balikun area of Eastern Tianshan Orogen. Of which, LA–ICP–MS zircon U‐Pb isotopic dating from the diorites revealed that they were emplaced at 327∼333 Ma, representing an important period of magmatism in the Early Carboniferous. Geochemically, they are characterized by moderate SiO2 (51.33–62.48 wt%), high but variable MgO (2.04–11.16 wt%, average 5.35), higher Mg# (40–73) and TiO2 (0.67–1.29 wt%), Na2O/K2O (1.39–2.95) as well as variable Cr (2.49–675 ppm) and Ni (1.31–174 ppm), showing a geochemistry similar to those of high‐Mg diorites or sanukitoids. In addition, they are enriched in the LILE, poor HFSE with an evident negative Nb anomalies and a REE pattern of moderate fractionator between LREE and HREE without or weak negative Eu anomalies. Their ∊Hf(t) are positive (+3.63–+15.65), suggesting a source from the depleted mantle. In addition, they have high TiO2 and Pb, and large quantity of amphibolite and biotite, indicating that they were most likely derived from the partial melting of depleted mantle metasomatized by the slab‐derived melt under a hydrous condition. Consequently, combined with the contemporary volcanics and granitoids formed in the island arc settings, we proposed that the subduction was continued till Early Carboniferous in the Bogda‐Harlik tectonic belt. After that, wide occurrence of the post‐collisional A‐type granites and mafic‐ultramafic intrusions indicate this tectonic belt entered the post‐collisional environment from Late Carboniferous to Permian. [ABSTRACT FROM AUTHOR]

The North Qaidam orogenic belt (NQOB) lies at the northeast margin of Tibet Plateau, between the Qilian massif to the north and Qaidam massif to the south. It consists of predominantly gneisses and marbles with minor eclogite and garnet peridotite, and is known as an Early Paleozoic continental deep subduction ultrahigh pressure (UHP) metamorphic belt in northwest China. Recently some studies suggest that the NQOB experienced oceanic deep subduction prior to the continental deep subduction. However, the records of ocean events are rarely preserved because of the complex multi‐stage transformation. Therefore, whether the Early Paleozoic ocean exists and the formation, nature and evolution of the Early Paleozoic ocean in North Qaidam are still in controversies. In this contribution, we report a new discovered SSZ‐type ophiolite suite in Kaipinggou area, the western segment of the NQOB. The ophiolite is mainly composed of peridotite, gabbro, basalt, boninite, andesitic porphyrite and plagiogranite. In which, the basalt and homogeneous gabbro are both enriched in LILE and depleted in HFSE, and display flat or LREE‐depleted REE patterns, similar to the MORB‐like geochemical characteristics of fore‐arc basalts; the boninite exhibits characteristics of fore‐arc boninites with high Si and Mg, but low Ti and Ca contents; the andesitic porphyrite is enriched in LILE but depleted in HFSE, similar to island arc magmatic rocks. Rock assemblage and their geochemical characteristics suggest that this SSZ‐type ophiolite was formed in fore‐arc setting of intra‐oceanic arc. The plagiogranite is a low‐potassium tholeiite metaluminous granite with low trace elements contents, slight enrichment of LREE, depletion of HREE and positive Eu anomaly; combining with ∊Hf (t) values (13.8–17.1) of zircons, the plagiogranite could be originated from partial melting of gabbros. LA–ICP–MS zircon U–Pb dating yielded the crystallization ages of 535±2 Ma, 513±3 Ma and 510±3 Ma for two cumulate gabbros and one homogeneous gabbro, respectively, and a formation age of 492±8 Ma for the plagiogranite. All these data suggest the existence of an Early Paleozoic ocean in the North Qaidam, and the initial subduction of the oceanic slab occurred earlier than 535Ma. [ABSTRACT FROM AUTHOR]

The article discusses research on geochemistry of Cu-Ni (PGE) Sulfide-bearing mafic-ultramafic rocks in the middle of Inner Mongolia. Topics discussed include analysis of shapes and composition of ore-bearing intrusions on the mafic-ultramafic belt, dating of ore-bearing intrusions by uranium-lead dating method and impact of crustal contamination on intrusions.

The article presents a study on geochemistry and zircon uranium-lead (U-Pb) dating of banded iron formation (BIF) wall-rocks from Huoqiu iron ore field located in Anhui province, China. Topics discussed include the geological setting, collection of gneiss samples from three deposits including Taoba, Zhangzhuang and Bantaizi deposits and chemical compositions of Huoqiu BIF wall -rocks indicating their protoliths belong to calc-alkaline series.

The article presents a study on geochemistry and geochronology of andesite rock in Langlike copper deposit located in North Qilian Mountain, China. Topics discussed include characteristics of andesite rock such as massive structure and porphyritic structure, geochemical characteristics of andesite rock such as magnesium, and the use of Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) zircon uranium-lead (U-Pb) dating tests to conduct the study.

The article presents a study on uranium?lead (U-Pb) dating and laser ablation?inductively coupled plasma?mass spectrometry (LA-ICP-MS) of Middle Permian granite of Langshan Mountain, China and its indicating significance. Topics discussed include characteristics of granite such as finegrained texture and massive structure; chemical composition of granite and selection of zircon to carry on LA-ICP-MS U-Pb dating.

The article discusses geochemical characteristics of granitoids rock by zircon uranium-lead dating in the Jinchang copper-gold deposit, Heilongjiang Province, China. Topics discussed include division of intrusive boies into five periods by diagenetic age, formation of granitoids since collisional regime of magma-fluid in the Jinchang mining area, and the metallogenic age of the Jinchang copper-gold deposit.

The Russian Far East and Northeast (NE) China are located in the eastern part of the Central Asian Orogenic Belt (CAOB), which consists of a series of micro-continental massifs including the Erguna, Xing'an, Songnen-Zhangguangcai Range, Bureya, Jiamusi, and Khanka massifs. The Khanka Massif is located in the easternmost part of the CAOB, mainly cropping out in the territory of Russia, with a small segment in NE China. To the north and west of the Khanka Massif are the Jiamusi and Songnen-Zhangguangcai Range massifs, respectively. The boundary between these massifs is marked by the Dunhua-Mishan Fault. To the south lies the North China Craton, and to the east is the Sikhote-Alin Orogenic Belt separated by the Arsenyev Fault. However, the early Paleozoic evolution and tectonic attributes of the Khanka Massif are debated. These conflicting ideas result from the lack of systematic research on early Paleozoic igneous rocks from the Russian part of the Khanka Massif. It is generally accepted that the CAOB represents the largest known Phanerozoic accretionary orogenic belt. However, questions remain concerning the nature of the deep crust beneath the Khanka Massif, and whether Precambrian crust exists within the massif itself. In this paper, we report new zircon U-Pb ages, Hf isotopic data, and major- and trace-element compositions of the early Paleozoic intrusive rocks from the Khanka Massif of the Russian Far East, with the aim of elucidating the early Paleozoic evolution and the tectonic attributes of the Khanka Massif, as well as the nature of the underlying deep crust. New U-Pb zircon data indicate that early Paleozoic magmatism within the Khanka Massif can be subdivided into at least four stages: ∼502 Ma, ∼492 Ma, 462-445 Ma, and ∼430 Ma. The ∼502 Ma pyroxene diorites show negative Eu anomalies, and the ∼492 Ma syenogranites, intruding the ∼502 Ma diorites, show positive Eu anomalies. These observations indicate that the primary parental magmas of these rocks were derived from different origins. The 462-445 Ma magmatism is made up of syenogranites and tonalites. The ∼445 Ma Na-rich tonalites contain low REE concentrations, and are enriched in Eu and Sr. These observations, together with the positive εHf(t) values, indicate that they were derived from magmas generated by partial melting of cumulate gabbros. The ∼430 Ma I-type granodiorites and monzogranites from the northern Khanka Massif, and the A-type monzogranites from the central Khanka Massif display zircon εHf(t) values ranging from −5.4 to +5.8. This suggests that they formed from magmas generated by partial melting of heterogeneous lower crustal material. Zircon Hf isotopic data reveal the existence of Precambrian crustal material within the Khanka Massif. The geochemistry of the Middle Cambrian intrusive rocks is indicative of formation in an extensional setting, while Late Cambrian-middle Silurian magmatism was generated in an active continental margin setting associated with the subduction of a paleo-oceanic plate beneath the Khanka Massif. Regional comparisons of the magmatic events indicate that the Khanka Massif has a tectonic affinity to the Songnen-Zhangguangcai Range Massif rather than the Jiamusi Massif. [ABSTRACT FROM AUTHOR]

The article presents a study of Yangla copper deposit in Yunnan Province, China highlighting its diagenesis, mineralization, ore-prospecting and tectono-geochemistry. The diagenesis age of gabbro-diabase dikes is noted to be consistent with the granodiorite ages based on the results of zircon uranium-lead dating. Copper mineralization is found to be associated with quartz porphyries and shows that Yangla copper ore has undergone tectonic movements.